1. Field of the Invention
The invention is based on a fuel injection device for an internal combustion.
2. Description of the Prior Art
A fuel injection device of this kind is known from DE 103 43 482 A1. This fuel injection device has a delivery pump, which is equipped with an electric drive unit and delivers fuel from a fuel tank to the intake side of a high-pressure pump. The high-pressure pump delivers fuel into a high-pressure region; in the high-pressure region, at least one injector is provided, which is situated on the internal combustion engine and injects fuel into the engine. The fuel injection device also has an electronic control unit that controls the fuel injection as a function of operating parameters of the internal combustion engine. Between the delivery pump and the intake side of the high-pressure pump, a fuel metering device is provided, which is triggered by the electronic control unit and is able to vary the fuel supply to the intake side of the high-pressure pump and therefore the fuel quantity that the high-pressure pump delivers into the high-pressure region. In the high-pressure region, a pressure sensor is provided, which is connected to the electronic control unit and detects the pressure in the high-pressure region; the control unit triggers the fuel metering device so that the high-pressure pump supplies the high-pressure region with the fuel quantity that is required to maintain a predetermined pressure in the high-pressure region. The delivery pump is operated at an essentially constant speed so that it delivers an essentially constant fuel quantity that must be dimensioned so that the maximum fuel demand of the internal combustion engine is made available. As a result, the delivery quantity of the delivery pump is too large in most operating states of the engine other than full load. The excess fuel quantity of the fuel pump is diverted into a pressure-relief region by an overflow valve situated between the delivery pump and the fuel metering device. The delivery pump in this case must be very large and must be dimensioned for a corresponding long-term load, which results in high manufacturing costs and a high electrical power demand for its operation.